Continuous composite rod and methods

ABSTRACT

A continuous composite fiberglass sucker rod for connection between a pump and a pump drive has a rectangular cross section. End fittings having a rod receiving cavity are connected to the rod ends using a curable adhesive. The rod fitting is maintained in a vertical position with the cavity facing upwardly. The rod end portion is positioned in the cavity with the end at the bottom of the cavity. Curable adhesive is introduced into the cavity. A centralizer bushing is used to maintain alignment of the rod relative to the cavity. A portable heating device receives the fitting and rod end portion and enhances the curing process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application PCT/US2010/034703 withan international filing date of May 13, 2010, which claims prioritypursuant to Title 35 USC 119(e) to U.S. Provisional Application No.61/178,295 filed May 14, 2009, entitled “Continuous Composite SuckerRod.” The entire specification and drawings of the aforementionedapplication is incorporated by reference herein as if fully set forth.This application is related to U.S. Utility application Ser. No.12/779,260 filed May 13, 2010, issued as U.S. Pat. No. 7,972,462 on Jul.5, 2011, entitled “Continuous Composite Rod and Methods.”

BACKGROUND OF THE DISCLOSURE

This disclosure relates to continuous composite fiberglass rod for wellpump drives and to apparatus and a method for attachment of end fittingsto the rod.

During production of a well, for example an oil well, the pressure fromthe well reservoir often becomes insufficient to transport hydrocarbonsto the surface without the assistance of a pump. In such cases, adownhole pump is typically lowered into the well, attached to the lowerend of a sucker rod string. The upper end of the rod string is thenattached to a pump jack or similar reciprocating surface apparatus.Through reciprocation of the pump jack, the rod string is used to drivethe downhole pump, enabling continued production of the well.

Conventionally, sucker rods are formed from lengths of steel, typicallyabout twenty-five (25) feet in length, which are connected to adjacentsteel rods using cylindrical, metal end fittings. Steel is inherentlyheavy. A steel sucker rod requires sizeable equipment and a significantquantity of energy to reciprocate. Further, steel sucker rods weaken andeventually fail after substantial exposure to the corrosive environmentwithin a well, causing steel sucker rods to frequently requirereplacement. Weakened and failed rods also often cause damage equipmentand necessitating difficult and expensive removal operations.Additionally, the assembly of steel sucker rods and the repair ofdamaged steel sucker rods requires bulky equipment and precisionwelding, among other factors, which prevents the rapid and efficientconstruction and repair of steel sucker rods in the field.

To overcome the drawbacks relating to the use of steel sucker rods,fiberglass sucker rods were developed. Composite fiberglass rods providesufficient strength to withstand axial loads similar to those of steelsucker rods while weighing considerably less. While a steel rod weighsapproximately 2.9 pounds per foot when immersed in well fluid, afiberglass rod of comparable length weighs only. 0.8 pounds per foot,resulting in a significant reduction in operational expenses relating tothe energy required to reciprocate the rod. Lighter fiberglass rodsegments are also easier and less expensive to transport, and easier andmore efficient to handle and install. Additionally, fiberglass resiststhe corrosive effects of the well environment. Further, compositefiberglass rods exhibit improved flexibility and elasticity over steelrods, resulting a greater effectiveness per stroke of a pump jack.

A conventional fiberglass sucker rod string is formed from cylindricalfiberglass rod segments about 37.5 feet long and about 0.875 inches indiameter, each formed from bundles of glass filaments approximately 15microns in diameter that have been wetted with a resin and formed into arod via a pulltrusion process. Multiple round fiberglass rod segmentsare connected together using steel end fittings similar to those used toconnect segments of steel rod, to form a multi-segment string ofsufficient length to connect a pump jack and a downhole pump. To formthe fiberglass sucker rod string, each rod segment must be individuallyconnected to two end fittings, which are adapted to engage similar endfittings in adjacent rod segments. A curable adhesive, such as epoxy, isnormally introduced into an end fitting, and a segment of fiberglass rodis then inserted. Once the adhesive cures, it binds to the fiberglassrod, forming a hardened plug that prevents removal of the rod from theend fitting during pumping operations.

U.S. Pat. No. 4,360,288, the entirety of the specification and drawingsof which are incorporated herein by reference, describes a fiberglasssucker rod construction that includes a cylindrical fiberglass rod bodyhaving a steel fitting member adhesively bonded to each end thereof. Thefitting members have internal receptacles with tapered annular spacesfor receiving an epoxy to bond the fiberglass rod, forming wedge-likeshapes of cured epoxy to prevent removal of the rod during operation.

U.S. Pat. No. 4,919,560, the entirety of the specification and drawingsof which are incorporated herein by reference, describes an oil wellsucker rod that includes a fiberglass rod with steel fittings on eachend. An annular centering surface and a plurality of dimples within thefitting serve to center the rod at two points within the fitting, whiletaper angles of the interior tapered surfaces decrease progressivelytoward the open end of the fitting.

U.S. Pat. No. 6,193,431, the entirety of the specification and drawingsof which are incorporated herein by reference, describes a fitting forconnecting rods, and a sucker rod construction using the fitting. Theinterior cavity surface of the fitting is shaped to form one or moreannuluses between the inserted rod and the fitting to form axiallyaligned wedges having a wide portion that narrows toward the open end ofthe cavity and approaches the rod, asymptotically.

Application for U.S. patent Ser. No. 11/715,085, filed Mar. 5, 2007,describes a continuous non-round composite fiberglass sucker rodconnected within a metal fitting using a curable adhesive. The fittingincludes a rod interior cavity or receptacle shaped to form one or moretapered cylindrical wedges having a wide portion that narrows toward theopen end of the fitting. The cavity contains the adhesive and the end ofthe rod.

The advantages of a sucker rod string formed from multiple segments offiberglass rod over a conventional steel sucker rod are numerous.However, a continuous fiberglass rod that extends from the surface of awell to the downhole pump with no interconnections or jointstherebetween thereby requiring only the single connection at each end toconnect the pump jack to the downhole pump is even more advantageous. Acontinuous fiberglass rod is significantly easier and less expensive tostore, handle, transport, and install by eliminating the time,materials, space, and labor required to create a large number ofinterconnections between each rod segment.

Early attempts to create continuous composite fiberglass rodsencountered numerous difficulties and failures. While fiberglass rod isable to withstand a significant axial load, equal to that of a steelrod, early fiberglass rods, known as ribbon rods, readily cracked orbroke if twisted, or bent beyond tolerance. Thus, when attempting tocoil a continuous fiberglass ribbon rod about a spool, an impracticallylarge spool is required to avoid coiling the rod beyond its tolerance.With ribbon rod, normally stored on a spool in a single wrap asillustrated in U.S. Pat. No. 4,563,391, a very limited amount offiberglass ribbon rod could be spooled. The weight of exterior layers ofrod on the spool cracks interior layers.

Existing fiberglass sucker rod systems employ rod having a generallycylindrical rod, with a round cross section. However, it has beendetermined that the ability of a fiberglass rod to withstand the axialloads inherent in downhole pumping operations depends primarily on thecross sectional area of the rod, rather than the shape of the rod. Thus,it is possible to create a composite fiberglass rod having a non-roundcross section, thereby having different bending moments of inertia indifferent bending directions, depending upon the cross-sectional shapeof the rod, enabling a composite fiberglass rod having a suitablecross-sectional shape to be coiled about a spool without damaging therod, to withstand the weight of exterior layers of rod on the spoolwithout cracking, and to withstand the weight of a dispensed portion ofthe rod on the spooled portion of the rod without breaking.

For example, a conventional fiberglass sucker rod, having a round crosssection, would have an bending moment of inertia in any direction. Around fiberglass rod approximately 0.5 inches in diameter would requirea spool eight feet in diameter to coil the rod without causing damage,Conversely, a composite fiberglass rod having a rectangularcross-section that is 0.375 inches by 1.75 inches could be successfullycoiled on a spool as small as forty eight inches (48″) in diameter.

Conventional end fittings or fittings are designed to accommodatecylindrical rods, having a generally round cross section. To date, nomethod or system exists for creating sucker rod constructions, orsimilar assemblies, from non-round composite fiberglass rods and/orrepairing composite fiberglass rods having a non-round cross sectionutilizing conventional end fittings.

Conventional systems and methods for assembling and repairing sucker rodassemblies require cumbersome and bulky equipment, thereby restrictingthe creation and/or repair of sucker rods to designated locationsconfigured for such a purpose. To date, no portable method or systemexists for creating sucker rod constructions from composite fiberglassrods and/or repairing composite fiberglass rods in the field.

A need exists for a method usable to create a composite fiberglass rodhaving a non-round cross section, thereby exhibiting improvedflexibility, and storage ability, while retaining an equal or greateraxial strength than a comparable round rod.

A need also exists for a method for forming a composite fiberglass rodhaving a non-round cross section suitable for the formation of acontinuous fiberglass rod, lacking any intermediate fittings or joints,thereby conserving the time and labor relating to assembly of sucker rodrings.

Use of such a non-round composite fiberglass rod would enable acontinuous composite fiberglass rod to be constructed, extending fromthe surface of a well to the downhole pump with no interconnections orpoints therebetween, thereby requiring only the single fitting at eachend to connect the pump jack to the downhole pump. Continuous fiberglassrods would be significantly easier and less expensive to store, handle,transport, and install, compared to noon-continuous rods, and wouldeliminate the time, materials, space, and labor required to create alarge number of interconnections between each rod segment. Further, alarge quantity of continuous composite fiberglass rod can be wrappedaround a spool for facilitating storage and installation, due to theimproved bending radius of the non-round composite fiberglass rod.

A need exists for a composite fiberglass rod usable to actuate adownhole pump, having a non-round cross section, thereby exhibitingimproved flexibility, and storage ability, while retaining an equal orgreater axial strength than a comparable round rod.

A need also exists for a composite fiberglass rod having a non-roundcross section, suitable for the formation of a continuous fiberglassrod, lacking any intermediate fittings or joints, thereby conserving thetime and labor relating to assembly of sucker rod strings.

A need also exists for a composite fiberglass rod having a non-roundcross section that is usable with conventional sucker rod systems andfittings including the conventional steel end fittings, as well as othertypes of fittings and system components.

A need also exists for a system and method that can evenly heat aquantity of curable adhesive, at a uniform and controlled temperature,to efficient provide an effective connection between a fiberglass rodand an end fitting.

A need exists for a portable system and method that is usable in thefield to quickly and efficiently secure an end fitting to a compositefiberglass rod using a curable adhesive.

A further need exists for a system and method that can secure an endfitting to a composite fiberglass rod when the end fitting has a crosssectional shape different from that of the rod.

The present embodiments meet these needs.

SUMMARY OF THE DISCLOSURE

The embodiments of the present disclosure include a method for forming acomposite fiberglass rod for use in actuating a downhole pump. Acontainer is provided, the container having a resin therein. The resincan include an adhesive, an epoxy, a polymer, a composite, orcombinations thereof. The container can have any shape or volume,depending on the quantity and type of composite fiberglass rod to beproduced, and the nature of the operations to be undertaken. Thecontainer can be integral with or in communication with one or moreheating devices, mixing devices, compression devices, or other equipmentto facilitate the movement and use of materials and production of thecomposite fiberglass rod.

A composite fiberglass rod is provided for use actuating a downholepump. The composite fiberglass rod can be formed from fiberglass fibersarranged in a parallel bundle, incorporated into a matrix, or othersimilar materials. Typically, a composite fiberglass rod can be formedby wetting glass filaments, or rovings in a resin, then extruding orpulltruding the mixture while curing the resin, to form a shaped rod.

Multiple rovings of fiberglass can be submerged in the resin. Eachroving can be formed from 240 to 280 glass fibers that are coiledtogether, and 150 rovings, or more, can be combined to form a compositefiberglass rod. In an embodiment, from 240 to 280 rovings of fiberglasscan be submerged in the resin. The number of fibers per roving, and thenumber of rovings used to construct a rod can vary depending on thedesired length and diameter of the rod and the nature of the operationsto be performed using the rod. For example, a composite fiberglass rodmanufactured to withstand extreme temperatures can be formed from alarger number of rovings than a standard composite fiberglass rod.

The rovings and resin are then pulled through at least one shaped holein the container to form a strand of fiberglass, that is heated to forma composite fiberglass rod. Heat can be provided using a heated die,heat generated by the shaped opening, one or more heating devices incommunication with the container, other similar heat sources orcombinations thereof. The rate of the pulling of the rovings and resinthrough the shaped hole can be controlled to allow curing of the resinto form the rod, depending on the curing time and temperature necessaryfor the mixture of rovings and resin.

In an embodiment, the rovings can be arranged in a parallel bundle,prior to pulling, to prevent looping and flaws in the resultingcomposite fiberglass rod. A matting bar or similar apparatus can be usedto engage the ravings to prevent tangling and/or looping.

Once pulled through the shaped opening, a desired length of compositefiberglass rod can be cut. In an embodiment, the formed compositefiberglass rod can be wrapped around a spool while pulling the rovingsand resin through the shaped opening. Once the rod is engaged with thespool, the spool can be used to continue pulling the rovings and resinthrough the shaped opening while wrapping the composite fiberglass rodaround the spool. In an embodiment, the spool can be laterally moveableon a central axis, enabling the composite fiberglass rod to be pulledfrom the container without bending the rod, while the movement of thespool enables adjacent wraps of rod to be layered about the spool.

The shape of the opening in the container can be selected to provide thecomposite fiberglass rod with a non-round cross section, in which afirst distance extends in a first direction between opposite sides,while a second distance extends in a second direction substantiallyperpendicular to the first direction between corresponding oppositesides. The non-round cross section can include any polygonal shape otherthan circular, for providing the rod with a lower bending moment in onedirection when compared to the bending moment of another direction. Forexample, the non-round cross section can be rectangular, or elliptical.Alternatively, the non-round cross section can be a vertically curvedshape, that is one of the opposite sides is convex and the other concaveenabling mating between overlapping vertical layers of rod on a spool.The non-round cross section can be a horizontally curved shape, forexample, in a rectangular rod, one short side can be convex and theopposite short side concave, enabling mating between laterally adjacentwraps on a spool.

The present embodiments enable production and use of a compositefiberglass rod that is continuous, usable to actuate a downhole pumpusing a surface reciprocating device with substantially nointerconnections therebetween. Due to the unique non-round crosssectional shape of the composite fiberglass rod, a single spool cancontain up to 15,000 feet, or more, of a continuous fiberglass rodwithout cracking or breaking the rod. Due to the ability of thefiberglass rod to engage end fittings using a curable adhesive, thepresent embodiments enable the assembly and/or repair of sucker rodconstructions in the field. These and other advantages of the producedcomposite fiberglass rod will become evident in the foregoingdisclosure.

In an embodiment, the ratio of the first distance across the non-roundcross section to the second distance across the non-round cross sectioncan range from 3 to 1 to 10 to 1. The second distance can range from0.125 inches to 0.75 inches. The first distance can range from 0.625inches to 5.0 inches. For example, a useful composite fiberglass rod canhave a rectangular cross section with sides of a length of about 1.0inch and sides defining a thickness of about 0.25 inches. This is aratio of 4:1.

The non-round shape of the composite fiberglass rod provides the rodwith a bending moment along a first axis greater than that along asecond axis, enabling the rod to be wrapped around a spool and/ordispensed into a well without cracking or breaking. The non-round shapeof the composite fiberglass rod enables the rod to be manufactured andutilized a continuous fiberglass rod, extending from a reciprocatingsurface apparatus to a downhole pump with substantially nointerconnections.

An end fitting is provided for attachment to each end of the compositefiberglass rod. The end fitting is adapted for securing to areciprocating surface apparatus and/or a downhole pump. It has a cavitytherein, with dimensions sufficient to accommodate the end of thecomposite fiberglass rod. The cavity does not have a shape similar tothat of the cross-section of the rod, however the cavity defines anopening equal to or greater in dimension than the largest dimension ofthe cross section of the composite fiberglass rod. The cavity is shapedsimilarly to that disclosed in U.S. Pat. No. 6,193,431 and applicationfor U.S. patent Ser. No. 11/715,085. That is, the cavity has pockets tocontain curable adhesive to retain the rod end within the fitting.

The end fittings can be formed from metal, can have any shape, includinga generally round cross section. For example, a cylindrical end fittinghaving a cavity opening minimum diameter of one inch can be used tosecure to an end of a composite fiberglass rod having a rectangularcross section with a length of 1.0 inch and a thickness of 0.25 inches.

Curing the adhesive can include providing heat using a portableapparatus, a chemical reaction, ambient energy, or combinations thereof.In an embodiment, a curable adhesive, such as an epoxy, can be used toaffix the composite fiberglass rod within the end fittings. Typically,the curable adhesive is initially a liquid that is introduced into theinterior of an end fitting. The rod is inserted, compressing theadhesive against the interior surface of the end fitting.

As the curable adhesive cures, it binds to the fiberglass rod, formingone or more plugs or wedge-like sections, which prevents removal of therod from the end fitting.

Adhesives that are curable by heat, such as that from a portable heatsource, ambient heat, or that of an exothermic chemical reaction, suchas a two-part epoxy, can be used to enable the end fitting to beattached to the composite fiberglass rod in the field. The ability toassemble and/or repair fiberglass sucker rods in the field is asignificant advantage over conventional steel sucker rods, which oftenmust be welded prior to transport.

Usable adhesives could also include polymer adhesives, includingpolyurethane or one or more plastics, a multi-part or multi-stepadhesive, or other similar adhesives. Typically, the curable adhesive isinitially a liquid that is introduced into the cavity of the endfitting. The rod is then inserted, compressing the adhesive against theinterior surface of the cavity.

The adhesive can then be cured by adding a second component, performingadditional steps, or through the passage of time and/or the exposure ofthe adhesive to ambient conditions. For example, the curable adhesivecan cure through a chemical reaction, such as an exothermic chemicalreaction that produces sufficient heat to cure the curable adhesive. Tosecure the fitting and sucker rod, a curable adhesive is introduced intothe cavity. An end of a composite fiberglass rod having a non-roundcross section, as previously described, is inserted into theadhesive-filled cavity. Insertion of the rod compresses the curableadhesive toward the interior surface of the end fitting cavity. Thecurable adhesive is then cured, causing the adhesive to bond to thecomposite fiberglass rod, thereby preventing removal of the rod from theend fitting during reciprocation operations.

In an embodiment, the interior of the cavity of the end fitting caninclude one or more interior protrusions, wedges, annuluses, or similarregions that enable the adhesive to form wedge-shaped protrusions whencured. The interior protrusions and/or spaces can also serve to centerthe rod within the end fitting while the adhesive cures. As the curableadhesive cures, it binds to the fiberglass rod, forming one or moreplugs or wedge-like sections, which prevents removal of the rod from theend fitting.

One or more clamps or other objects adapted for gripping the compositefiberglass rod could also be used to center and secure the rod duringcuring of the adhesive. When attaching an end fitting to a continuousfiberglass rod disposed around a spool, the spool can be used tomaintain the rod in a vertical orientation during curing of theadhesive.

The system can also include a centralizing bushing, collet, or similarstructure adapted to secure to the end fitting, having a cavity thereinfor accommodating the rod end and centering the rod within the endfitting during curing of the adhesive. The centralizing bushing orcollet can be removable after the adhesive cures. For example, a bushinghaving a rectangular slot and a partial or bore therethrough can be usedto engage a fitting adjacent the cavity opening and a compositefiberglass rod having a rectangular cross section to maintain theirproperly aligned relationship during the curing process.

In an embodiment, the method can include centering the compositefiberglass rod within the cavity while curing the adhesive, through useof clamps, bushings, interior protrusions within the cavity, orcombinations thereof. The method can also include maintaining the rod ina vertical orientation during curing of the adhesive, such as throughuse of clamps, a spool, or similar methods of retaining the rod in avertical position.

The present embodiments include a portable heating system for attachinga composite fiberglass rod to an end fitting.

In an embodiment, a portable heating apparatus can be used, theapparatus having a receptacle adapted to contain the end fitting withthe curable adhesive and the end of the fiberglass rod disposed therein.A heating member within the apparatus can then evenly heat thereceptacle to evenly cure the adhesive.

In an embodiment, the system can include a support configured to retainthe end fitting in a vertical orientation. The support can be portable,weighing twenty pounds or less, to facilitate the portability of thepresent system and enable use of the present system on-site, in thefield.

The present system further includes a portable heating device, having anopening with dimensions sufficient to accommodate the end fitting withthe curable adhesive and composite fiberglass rod therein. The portableheating device includes a heating member for providing heat to theopening to evenly heat the end fitting and cure the curable adhesive.

In an embodiment, the portable heating device can have a fluid media,such as a petroleum product, therein to provide a uniform temperature tothe end fitting, enabling even heating and providing control over thetemperature of the heating. The heating device can be in communicationwith a processor, which is usable to control the temperature provided bythe heating device.

Portable heat sources enable construction and/or repair of fiberglasssucker rod assemblies to be performed rapidly and efficiently, on-site,in the field, and enable the rod and end fitting to be utilizedimmediately after assembly and/or repair. The present embodimentsthereby enable on-site production and use of composite fiberglass rodsand attached end fittings.

The method can further include controlling the temperature provided bythe portable heating device, which in an embodiment, can range from 300degrees Fahrenheit to 400 degrees Fahrenheit. In a further embodiment,the heat from the portable heating device can be provided for a timeranging from 30 minutes to 60 minutes.

The present embodiments thereby enable on-site production and use ofcomposite fiberglass rods and attached end fittings, usable to actuate adownhole pump using a surface reciprocating device. The rod and be acontinuous fiberglass rod, requiring only two end fittings for attachingto the downhole pump and the surface reciprocating device. Due to thenature of the curable adhesive and portable heating device, the presentsystem and method can form reliable connections between end fittings andcomposite fiberglass rods having similar or differing cross sectionalshapes in the field. These and other advantages of the present systemand method will become evident in the foregoing disclosure.

The present embodiments thereby enable production and use of a compositefiberglass rod that is continuous, usable to actuate a downhole pumpusing a surface reciprocating device with substantially nointerconnections therebetween. Due to the unique non-round crosssectional shape of the composite fiberglass rod, a single spool cancontain up to 15,000 feet, or more, of a continuous fiberglass rodwithout cracking or breaking the rod. Due to the ability of thefiberglass rod to engage end fittings using a curable adhesive, thepresent embodiments enable the assembly and/or repair of sucker rodconstructions in the field. These and other advantages of the presentcomposite fiberglass rod and related systems will become evident in theforgoing disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of the embodiments presented below,reference is made to the accompanying drawings, in which:

FIG. 1 is a schematic view of a system utilizing a continuous compositefiberglass rod with field-installable end fittings, in accord with anembodiment of the present disclosure.

FIG. 2 is a cross-sectional view of the continuous composite fiberglassrod of FIG. 1.

FIG. 3 is a cross-sectional view of another embodiment of the continuouscomposite fiberglass rod.

FIG. 4 is a cross-sectional view of another embodiment of the continuouscomposite fiberglass rod.

FIG. 5 is a side elevational view, partially in section, of an endfitting of the present disclosure with a non-round continuous compositefiberglass rod installed in the receptacle cavity of the fitting.

FIG. 6 is an end view, in section, of an embodiment of the continuouscomposite fiberglass rod within an end fitting taken along line 6-6 ofFIG. 5.

FIG. 7 is a side cross-sectional view of an embodiment of a portableheating apparatus with an end fitting and a composite fiberglass roddisposed therein, usable with the present system and method.

FIG. 8 is a front view of the centralizer bushing of the presentdisclosure.

FIG. 9 is a side view of a centralizer bushing of the presentdisclosure.

FIG. 10 is a cross-sectional side view of the end fitting of FIGS. 2 and3 with the centralizer bushing of FIGS. 8 and 9 attached.

The present embodiments are detailed below with reference to the listedfigures.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Referring now to FIG. 1, an embodiment of a system for producing a wellis shown, which includes a composite fiberglass rod 100 within awellbore 133. The composite fiberglass rod 100 is depicted as acontinuous rod, having a non-round rod cross-section, which engages thehead 200 of a pump jack 212 at the surface of the wellbore 133 andextends to the bottom of the wellbore to engage a downhole pump 136. Thecomposite fiberglass rod 100 extends between the pump jack 212 and thedownhole pump 136 with no interconnections therebetween, having an upperend fitting 230 engaging the upper end of the composite fiberglass rod100 and a lower end fitting 232 engaging the lower end of the compositefiberglass rod 100.

The continuous composite fiberglass rod 100 can be reciprocated usingthe pump jack 212 or any similar surface apparatus usable to raise andlower the composite fiberglass rod 100 to actuate the downhole pump 136.Typically, pump jack head 200 engages the composite fiberglass rod 100.A beam 216, and a counterweight 218, pivotally mounted to a supportframe 214 reciprocate the composite fiberglass rod 100. A pump jackmotor 221 is usable to pivotally move the beam 216.

As seen in FIG. 1, the head 200 of the pump jack 212 is connected to apolish rod 240. The polish rod 240 extends through a seal 260, which caninclude one or more pickoffs other similar types of sealing members.Typically, a polish rod is used with a pump jack system to provide aseal between the wellbore and the atmosphere.

Upper end fitting 230 is shown attached to the upper end of thecomposite fiberglass rod 100, engaged with the polish rod 240. The endfitting 230 can have male or female threads adapted to engagecomplementary threads on the polish rod 240. The end fitting 230 canfurther have threads on the end opposite the polish rod 240 for engaginga collet, bushing, or other similar structure for centering thecomposite fiberglass rod 100 within the end fitting 230.

A lower end fitting 232 is shown attached to the lower end of thecomposite fiberglass rod 100. The end fitting 232 can be of aconstruction similar to that of the upper end fitting, though in anembodiment, the lower end fitting 232 and first end fitting 230 can haveopposing threads. The lower end fitting 232 is depicted secured to thedownhole pump 136, such that reciprocation of the composite fiberglassrod 100 using the pump jack 212 actuates the downhole pump 136.

The composite fiberglass rod 100 can incorporate fiberglass fibers, orrovings, arranged in a parallel bundle, which are incorporated into amatrix. Any loops, tangles, spaces, gaps or other imperfections in therovings should be avoided to prevent structural weaknesses in thecompleted rod. Or, the composite fiberglass rod 100 can includecontinuous fibers, arranged in a longitudinal direction to providestrength to the rod.

From 240 to 280 glass fibers can be coiled to form a roving, and 150rovings, or more, can be combined to form a composite fiberglass rod.The number of fibers per roving, and the number of rovings used toconstruct a rod can vary depending on the desired length and diameter ofthe rod and the nature of the operations to be performed using the rod.For example, a composite fiberglass rod manufactured to withstandextreme temperatures can be formed from a larger number of rovings thana standard composite fiberglass rod.

The rovings can be wetted using a resin, such as an epoxy, a polyesterresin, and/or one or more plastics to form a matrix for supporting thefibers. The resin can be set using an external heat source, ambient heator light, and/or an exothermic chemical reaction. The resin providessupport to the fibers and maintains the shape of the rod. The compositefiberglass rod can be extruded or pulltruded to obtain a rod having acontrolled diameter, length, and cross sectional shape. For example, acomposite fiberglass rod having a rectangular cross sectional shapecould be pulltruded through a heated die having a rectangular openingthrough which the mixture of fiberglass and resin passes as the resin iscured, to form a rectangular rod. As the rod is pulltruded, varyinglengths of the rod can be cut, as needed. A continuous rod, as long as15,000 feet, or more, can be formed using the pulltrusion process. Thecontinuous rod can be wrapped around a spool as it is formed.

Referring now to FIG. 2, a cross sectional view of an embodiment of acomposite fiberglass rod 100 is shown. FIG. 2 depicts the compositefiberglass rod 100 having a rectangular cross sectional shape, with afirst side 138 opposite a second side 140, and a third side 142 oppositea fourth side 144. FIG. 2 depicts the first and second sides 138, 140having a length greater than that of the third and fourth sides 142,144. The length of sides 138, 140 represents the major dimension of therod 100. The length of sides 142, 144 represents the minor dimension ofthe rod 100. The ratio of the major dimension of the rod 100 to theminor dimension of the rod 100 can range from 3:1 to 10:1. The distancebetween the third and fourth sides 142, 144 comprises a first distanceextending in a first direction and the distance between the first andsecond sides 138, 140 comprises a second distance extending in a seconddirection, perpendicular to the direction of the first distance. Theratio of the first distance to the second distance can range from 3:1 to10:1.

The bending moment parallel to the first and second sides 138, 140 isless than that parallel to the third and fourth sides 142, 144, and lessthan that of a round rod of similar construction. In an embodiment, thelength of the first and second sides 138, 140 can be one inch (1.0″),while the length of the third and fourth sides 142, 144 can be onequarter inch (¼″), which provides the depicted composite fiberglass rod100 with a tensile strength equal to that of a round rod of similarconstruction having a diameter of about 0.55 inches. However, thebending radius of a ¼ inch by 1.0 inch rectangular composite fiberglassrod is approximately one third that of a 0.55 inch diameter round rod,enabling a ¼ inch by 1.0 inch rectangular rod to be wrapped around aspool of forty-eight inches (48″) in diameter without damaging orcracking the rod. A much larger spool would be required to accommodate around rod due to its larger bending radius, and the weight of multiplelayers of round rod around a spool would cause the interior layers ofrod to crack.

However, the composite fiberglass rod 100 can have any non-round shapeand dimensions sufficient to provide the rod with a greater bendingmoment in one direction than the bending moment in another direction.The ratio of the distance along one side of the rod to that of aperpendicular side can range from 10 to 1 to 3 to 1. The smallerdimension can range in length from 0.125 inches to 0.625 inches. Thelarger dimension can range in length from 0.5 inches to 5.0 inches.

Further, while FIG. 2 depicts the composite fiberglass rod 100 having arectangular cross sectional shape, it should be understood that thecomposite fiberglass rod 100 can have any non-round cross-sectionalshape. For example, as shown in FIG. 2, the corners 146, 148 and theopposing corners 146 a and 148 a of the composite fiberglass rod 100 canbe rounded to form an elliptical or oval shape. In another embodiment,shown in FIG. 3, the first side 138 a could be convex while the secondside 140 a is concave, forming curved shape that enables a matingengagement between overlapping stacked layers of rod on a spool. In afurther embodiment, shown in FIG. 4, the first and second sides 138 band 140 b are planar and the third side 142 b is convex while the fourthside 144 b is concave enabling mating between adjacent wraps on a spool.

FIGS. 5 and 6 illustrate end fitting 230 exemplary of end fittings 230and 232 attached to composite fiberglass rod 100 of FIG. 1. The endfittings may be configured as described in application for U.S. patentSer. No. 11/715,085 filed Mar. 5, 2007 entitled “Continuous Sucker Rodand Method of Using Same,” the entire specification and drawings ofwhich are incorporated herein by reference. While FIGS. 5 and 6 depictend fitting 230 as having a cylindrical metal body, it should be notedthat end fittings having any shape large enough to accommodate thecomposite fiberglass rod 100 can be used, and that any materialsignificantly durable to withstand reciprocation of the rod is usable.

The composite rod is rectangular in cross-section as depicted in FIGS. 2and 6. For purposes of illustration, composite rod 100 includes oppositesides 138 and 140 spaced a distance, the minor dimension of the rod, ofabout one quarter inch (¼″), and opposite sides 142 and 144 spaced adistance, the major dimension of the rod, of about one inch (1″).

The end fitting 230 includes an external substantially cylindricalsurface 380 terminating in an externally threaded upper end. End fitting230 also includes a pair of diametrically opposite flat surfaces 348 forenabling an oil field operator to attach a standard sucker rod wrenchfor connecting and disconnecting the individual sucker rod end fittingsfrom other components such as polish rod 240 and pump 136.

As seen in FIG. 5, the end fitting 230 is formed to define an open axialreceptacle cavity 300 or pocket for receiving an end portion 101 of therod 100. The axial receptacle cavity 300 is defined by a series ofgenerally cylindrical tapered surfaces 340, 440 converging toward theopen end which cooperate with the external surface of the rod 100 whenthe rod 100 is in position in the cavity 300 to retain the rod 100within the fitting 230. The rod receptacle cavity 300 of fitting 230 issized to receive the end portion 101 of rod 100. The minimum diameter ofthe cavity 300 is represented by Dm in FIG. 5. It is slightly largerthan the major dimension of rod 100, i.e. the length of sides 138 and140.

The sucker rod end fitting 230 of the present disclosure has an openaxially outer end 353 and a closed axially inner end 333 defined bypilot bore surface 334 sized slightly larger than the major dimension ofrod 100. A first generally cylindrical wedge defining surface 340 isproximal to the open end 353 and a second cylindrical wedge definingsurface 440 is distal to the open end 353, and proximal to the closedend 333. A transition surface 335 connects from said first surface 340to the second surface 440. Transition surface 336 is similarly shapedand extends from second annular surface or wedge 440 to cylindricalpilot bore surface 334.

Transition surface 335 and transition surface 336 are formed in theshape of a wave having and outward tapered portion nearer open end 353and inward tapered portion nearer the closed end 333. Thus, thecross-section of surfaces 335 and 336 are preferably S-shaped,sine-waved shaped, or simply wave-shaped.

A curable adhesive 358 fills the cavity 300 between the rod end portion101 and the interior generally cylindrical surfaces 340, 440 andtransition surfaces 335 and 336. During assembly, the end portion 101 isinserted into the rod receptacle until the edge 103 of the rod endportion 101 is disposed adjacent closed end 333 of cavity 300 withinpilot bore surface 334. The rod end at edge 103 is centered within pilotbore surface 334. The sides 142 and 144 of rod 100 are also piloted bythe essentially cylindrical surface 340 at minimum diameter Dm. Suchengagement essentially by the sides 142 and 144 of the rectangular rodcenters the rod relative to the interior surfaces 340 and 400 andtransition surfaces 335 and 336 within cavity 300.

The composite fiberglass rod 100 displaces the curable adhesive 358 wheninserted into the end fitting 230, compressing the curable adhesive 358toward the interior surface of the end fitting 230 receptacle. Whencured, the curable adhesive 358 bonds with the composite fiberglass rod100 forming a plug or wedge-like shape between the interior of thereceptacle and the exterior of rod end portion 101 that prevents removalof the composite fiberglass rod 100 from the end fitting 230 duringpumping operations.

The curable adhesive 358 bonds to the composite fiberglass rod 100 toprevent removal of the composite fiberglass rod 100 from the end fitting230 during pumping operations. The curable adhesive 358 can be amultiple-component and/or a multiple-step adhesive, such as an epoxy.For example, a first component of the curable adhesive 358 can beintroduced into the end fitting 230 then the composite fiberglass rod100 can be inserted. A second component of the curable adhesive 358 canthen be introduced to cure the curable adhesive 358 and secure thecomposite fiberglass rod 100 within the end fitting 230.

The sucker rod end fitting 230 contains a sufficient quantity ofadhesive material 358 to completely fill the voids 324, 326 defined bythe fitting converging tapered surfaces 340, 440 and the outer surfaceof the rod 100 for interconnecting the rod 100 to the fitting 230. Whenthe end portion 101 of rod 100 is inserted into the receptacle, itdisplaces much of the liquid adhesive and forces it into the voids 324,326 surrounding the rod 100, where it subsequently cures, forming anangular wedge which is bonded to the rod 100. Since the rod 100 isrectangular, as illustrated in FIGS. 2 and 6, the wedges within thevoids 324 and 326 filled with adhesive material 358 are approximatelysemi-circular in cross-section as best illustrated in FIG. 6. The wedgesare widest in the radial direction between sides 138 and 140 of rod 100and surfaces 330, 440 and narrowest between sides 142 and 144 andsurfaces 330 and 440. In this latter relationship, the minimum gapbetween the sides 142 and 144 and the interior surfaces of thereceptacle would be the difference between the major dimension of therod, and the minimum diameter Dm of the cavity 300.

The end 101 of a rectangular rod 100 inserted into the cavity 300 orreceptacle of a fitting 230 or 232 is piloted, or essentially centeredby virtue of its contact along sides 142 and 144 with pilot bore surface333 and the closely spaced relation to the minimum diameter Dm withinthe cavity 300.

The cured adhesive material forms a sleeve having a series of taperingsurfaces defining a series of axially spaced wedges positioned betweenthe rod 100 and the receptacle tapered surfaces 340, 440. This hardenedadhesive sleeve forms a bond with the sucker rod 100 to resist the shearforce resulting when tension is applied to the rod 100, as if towithdraw it from the end fitting 230. Additionally, tension applied tothe rod 100 causes the wedges of cured adhesive material to be forcedinto compressive engagement with the rod outer surface and with thefitting member tapered surfaces 340, 440. This results in a compressionforce directed radially inwardly to the center line axis c-c of the endfitting 230 to compress the wedges of adhesive material against the rod100 to retain the rod 100 in position within the fitting member 230against the action of such tension applied to the rod 100.

To avoid the concentration of excessive force on the rod 100 from suchcompression, the wedges defined by surfaces 340, 440, as well astransition surfaces 335 and 336 must be formed such that there are noabrupt changes in the cross-sectional area of the adhesive 358. Thedesired effect of the wedges on the stress forces acting on them is todisperse the forces, not to concentrate them. The cross-sectional areaof the sleeve must change as smoothly as possible so that compressiveforces are dispersed equally along the end of the rod 100, and notconcentrated excessively at any portion of the rod 100.

Referring again to FIG. 1, preferably, a continuous sucker rod 100 isflexible enough to be wound on a large diameter reel in order totransport the continuous sucker rod 100 form the manufacturing facilityto the field for insertion into the wellbore 133. It should beappreciated, by those in the art, that a continuous sucker rod 100 wouldreduce the overall weight of the sucker rod string, since most of themetal end fittings are eliminated, and would reduce the handling time inthat numerous shorter lengths of sucker rods would not need to beattached, end to end, before, or as, the sucker rod is lowered into thewellbore 133. It should be further appreciated that the reels of thecoiled continuous sucker rod could be unloaded in the field forinsertion into the wellbore 133, or the reels could be mounted on atrailer such that the continuous sucker rod 100 would be uncoiled fromthe reel, which is mounted on the trailer, and inserted directly intothe wellbore 133. It is envisioned that a variety of methods could beutilized to uncoil the continuous sucker rod.

The non-round shape of the composite fiberglass rod 100 provides the rodwith a constant thickness, while having significant gripping surfacearea for a curable adhesive across the surfaces 138 and 140 of rod 100.These features cause the non-round composite fiberglass rod 100 to beeasier and less expensive to utilize.

The decreased weight of the composite fiberglass rod 100 versus aconventional steel sucker rod enables the rod to be spooled anddispensed three times as quickly, at one tenth the expense of aconventional steel sucker rod, without requiring a four-member workovercrew. In an embodiment, the composite fiberglass rod 100 can be removedfrom a well and repaired at a rate of 100 feet per minute. For example,when conducting repairs to a composite fiberglass rod within a 3,000foot well, the rod can be removed within 30 minutes, repaired within 10minutes, then reinserted within 30 minutes. The same repair for steelsucker rods would require a day and one half to complete.

A continuous composite fiberglass rod can be inserted or removed at arate of 6,000 feet per hour, with a single individual operating a spool.The spool can be as small as 48 inches in diameter, while containing15,000 feet, or more, of a continuous fiberglass rod, with the rod beingonly 75 inches thick on the spool. The depicted composite fiberglass rodthereby reduces transportation, storage, and installation time andrelated costs.

Additionally, due to the cross sectional configuration and compactnature of such a continuous fiberglass rod, and the ability of the rodto bend without cracking or breaking, a spool containing the continuousfiberglass rod can be mounted on a single trailer, coupled with aninjector, one or more clamps, or similar guides or other devices forcontrolling insertion of the rod into a wellbore. Conventional rodspooling systems require a significant distance between a spool of rodan and an injector device, and a second significant distance between theinjector device and the wellbore.

The composite fiberglass rod enables both a spool of continuous rod andan injector device or similar guide for controlling insertion of the rodto be placed within 50 to 60 feet of a wellbore. In an embodiment, thespool of rod can be placed as close as 2 feet from the wellbore.

Referring now to FIG. 7, a side cross-sectional view of an embodiment ofa portable heating apparatus 500 is shown, with an end fitting 230 and acomposite fiberglass rod 100 disposed therein. The portable heatingapparatus 500 is shown having a receptacle 520 sized to accommodate theend fitting 230. The receptacle 520 can have dimensions sufficient tocontain the entirety of the end fitting 230, or only a portion of theend fitting. The portable heating apparatus 500 further has a heatingelement 540, adapted to evenly heat the receptacle 520 from all sides,ensuring even curing of a curable adhesive 358 within the end fitting230.

In an embodiment, a fluid media, such as a petroleum product, can becontained within a portion of the portable heating device 500 forfacilitating controlled and even heating and curing of the curableadhesive 358 using a uniform temperature. The fluid media can beperiodically or continuously circulated throughout the portable heatingdevice 500 or stationary within the portable heating device 500.

The temperature of the heating element 540 can be controlled usingmanual or automatic means, and the controls can include use of acomputer or other device having a processor to monitor and/or regulatethe temperature provided by the portable heating device 500.

The end fitting 230 can optionally have a collet or centralizer bushingsecured thereon for centering the composite fiberglass rod 100 withinthe end fitting 230 while the curable adhesive 358 is cured. Thecomposite fiberglass rod 100 can also be retained in a centeredorientation within the end fitting using clamps or other devices adaptedfor gripping and holding the composite fiberglass rod 100.

The bending radius of the composite fiberglass rod 100 enables the rodto be secured within an end fitting while in a substantially verticalorientation. Conventional fiberglass rods must be secured to theirrespective fittings in a horizontal orientation, which createsdifficulty retaining liquid adhesives during the curing process, and canhinder retaining of the rod in a centered orientation within thefitting.

The centralizer bushing of the present disclosure is shown in FIGS. 8 to10. It is used to locate, and retain an aligned relationship between therod 100 and end fitting such as end fitting 230 or end fitting 232during assembly.

The centralizer bushing 400 is a cylindrical metal body 402 with apartial bore 404 open at one end of the body defining a cylindrical wall407 having an internal cylindrical surface 405 and a stop or bottomsurface 406. A threaded hole 408 open to bore 404 receives a set screw410.

The size, and depth of the partial bore 404 is sufficient to insert thefitting 230 until the open end 353 abuts stop or bottom surface 405. Theouter cylindrical surface 380 of fitting 230 is piloted by surface 405within the bore 404 in closely spaced relation, The diameter ofcylindrical surface 405 of cylindrical wall 407 is sized to be slightlylarger than the diameter of external cylindrical surface 380 of fitting230.

The overall length of the body 402 is about three times the depth of thepartial bore 404. A longitudinal slot 412 defined by slot wall surfaces401 and 403 extends the length of the body 402 through body 402including cylindrical wall 407. It thereby intersects bottom surface406. It has a width slightly larger than the minor dimension ofcomposite fiberglass sucker rod 100 between sides 138 and 140. That is,the slot wall surfaces 401 and 403 are spaced a distance to receive therectangular rod 100 with sides 138 and 140 facing wall surfaces 401 and403. Depth of slot 412 to transverse longitudinal surface 413 is suchthat the longitudinal surface 413 aligns with the surface within thereceptacle or cavity 300 of fitting 230 representing the minimaldimension Dm of the cavity 300. The overall depth of slot 412 relativeto the cylindrical surface 405 is one half the diameter of thecylindrical surface 405 plus one half the diameter Dm, the minimumdiameter of cavity 400 across generally cylindrical surface 440. It thusassures alignment of the rod 100 in a position equidistant from thesurfaces 340, 440.

Assembly of a fitting 230 to a rod 100 proceeds as described herein. Thefitting is positioned vertically with open end 353 facing upward. Thecavity 300 is filled with adhesive and the rod end 101 insertedcompletely into the cavity 300 until the end is centered by engagementwith pilot bore surface 334 and the surface within the cavity 300defining the minimum dimension Dm. Such insertion displaces adhesivefrom the cavity 300 to accommodate the volume of the inserted rod end101.

The centralizer bushing 400 is slid onto the rod 100 which passesthrough slot 412 until side 142 or 144 of the rod 100 contactslongitudinal surface 413 to align the bushing relative to the externalcylindrical surface 380 of fitting 230. The centralizer 400 is then slidlongitudinally along the rod 100 until the end 353 of fitting 400contacts bottom surface 406. The cylindrical surface 405 is thuspositioned in surrounding piloting relation to the external cylindricalsurface 353 of fitting 230 with rod 100 centered in the cavity 300relative to surfaces 340, 440.

The principal function of the centralizing bushing is to maintain properspacing between the tapered surfaces 340 and 440 and sides 138 and 140of the rod. It thus assures alignment of the rod 100 in a positionequidistant from the surfaces 340, 440.

Set screw 410 is tightened to temporarily affix the centralizer bushing400 to the fitting 230. The centralizer retains the proper alignment ofthe fitting 230 and rod end 101 during the curing process. Once theadhesive 358 is fully cured, the set screw 410 is loosened and thecentralizer bushing slid longitudinally until it clears the end offitting 230. It is then slid transversely of the rod 100 for removal andreuse.

Through use of a curable adhesive that bonds to the composite fiberglassrod 100, the present embodiments enable systems and methods forconstruction and/or repair of composite fiberglass sucker rod assemblieshaving end fittings, that can be performed rapidly, in the field,without requiring replacement parts or welding.

Through use of a portable heating device and a curable adhesive thatbonds to the composite fiberglass rod 100, the present embodiment enablesystems and methods for construction and/or repair of compositefiberglass sucker rod assemblies having end fittings, that can beperformed rapidly, in the field, without requiring replacement parts orwelding.

The foregoing disclosure and description of the invention is thereforeillustrative and explanatory of one or more presently preferredembodiments of the invention and variations thereof, and it will beappreciated by those skilled in the art that various changes in thedesign, organization, order of operation, means of operation, equipmentstructures and location, methodology, and use of mechanical equivalents,as well as in the details of the illustrated construction or combinationof features of the various elements, may be made without departing fromthe spirit of the invention.

Moreover, it will be understood that various directions such as “upper,”“lower,” bottom,” “top,” “left,” “right,” and so forth are made onlywith respect to easier explanation in conjunction with the drawings andthat the components may be oriented differently, for instance, duringtransportation and manufacturing as well as operation. Because manyvarying and different embodiments may be made within the scope of theinventive concept(s) herein taught, and because many modifications maybe made in the embodiment herein detailed in accordance with thedescriptive requirements of the law, it is to be understood that thedetails herein are to be interpreted as illustrative and not in alimiting sense.

As well, the drawings are intended to describe the concepts of theinvention so that the presently preferred embodiments of the inventionwill be plainly disclosed to one of skill in the art but are notintended to be manufacturing level drawings or renditions of finalproducts and may include simplified conceptual views as desired foreasier and quicker understanding or explanation of the invention. Aswell, the relative size and arrangement of the components may be greatlydifferent from that shown and still operate well within the spirit ofthe invention as described hereinbefore and in the appended claims. Itwill be seen that various changes and alternatives may be used that arecontained within the invention scope.

The invention claimed is:
 1. A centralizer bushing for securing a suckerrod within an end fitting, said bushing comprising: a solid cylindricalbody having ends, a partial bore open at one end of said body defined bya cylindrical wall having an internal cylindrical surface, and a bottomsurface spaced from said open end, a longitudinal slot extending throughsaid solid cylindrical body including said bottom surface, and saidcylindrical wall, said slot in said solid cylindrical body comprisingspaced facing wall surfaces and a transverse longitudinal surfacetherebetween, wherein the overall depth of the slot to said longitudinalsurface relative to the inner cylindrical surface of said partial boreexceeds one half of the diameter of said cylindrical surface definingsaid partial bore.
 2. A centralizer bushing as claimed in claim 1wherein said partial bore has a depth of about one-third the overalllength of the body.
 3. A centralizer bushing as claimed in claim 1wherein said slot includes facing walls in said body and saidcylindrical wall, and a transverse longitudinal surface in said body. 4.A centralizer bushing as claimed in claim 3 wherein the cylindricalsurface of said cylindrical wall is sized to receive the outercylindrical surface of an end fitting.
 5. In combination, a sucker rodend fitting and a centralizer bushing comprising: said end fittingincluding an outer cylindrical surface and defining a receiving rodcavity at one end thereof, said rod receiving cavity including at leastone surface defining a minimum diameter thereof, a centralizer bushingcomprising: a solid cylindrical body having ends, a partial bore open atone end of said body defined by a cylindrical wall having an internalcylindrical surface, and a bottom surface spaced from said open end, alongitudinal slot extending through said solid cylindrical bodyincluding said bottom surface and said cylindrical wall, said slot insaid solid cylindrical body comprising spaced facing wall surface and atransverse longitudinal surface therebetween wherein the overall depthof the slot to said longitudinal surface relative to the innercylindrical surface of said partial bore exceeds one half of thediameter of said cylindrical surface defining said partial bore.
 6. Acombination sucker rod end fitting and centralizer bushing as claimed inclaim 5 wherein said transverse longitudinal wall of said slot in saidbody is positioned to align with the surface within a fitting rod cavitydefining the minimum diameter of the cavity.